text data files

I am trying to create a text data file, file extension .dat.....how do I do this??
Basically, I am supposed to write a class in java, that reads from this text file, (the text file contains inventory information such as item name, # of units, price etc), and creates objects (of some class type which I am also supposed to create). So, taht's two classes........

If you want to learn about reading and writing files in Java, then have a look at Lesson: Basic I/O in Sun's Java tutorials. Especially the page Character Streams from that tutorial shows with examples how you can read and write text files.